1. Field of the Invention
The present invention relates to a piezoelectric microspeaker using microelectromechanical systems (MEMS) and a method of manufacturing the same and, more particularly, to a piezoelectric microspeaker manufactured using MEMS technology, in which a resonance frequency is changed in an audible frequency band, and a method of manufacturing the same.
This work was supported by the IT R&D programs of MIC/IITA. [2006-S-006-02, Components/Module technology for Ubiquitous Terminals]
2. Discussion of Related Art
Conventionally, methods of forming a small-sized microphone and a small-sized microspeaker on a silicon wafer using microelectromechanical systems (MEMS) technology have been disclosed. In these methods, since an acoustic transducer can be manufactured on a silicon wafer at one time, the manufacturing cost can be reduced. Also, a plurality of transducers and a plurality of amplifiers can be scaled down and integrated on a single chip so that a lot of advantages can be obtained as compared with conventional methods.
However, in a transducer manufactured using piezoelectric MEMS, since a diaphragm has residual tensile stress, a microphone has a relatively low sensitivity, while a microspeaker has a low output. Also, owing to miniaturization of the diaphragm, a plurality of resonance frequencies are included in an audible frequency band.
In addition to a compression diaphragm, tensile stress may be minimized using a wrinkling or hinge structure. However, manufacture of the wrinkling or hinge structure in MEMS using a semiconductor process takes additional costs. Therefore, it is necessary to develop a microspeaker that lowers production costs and makes no noise in an audible frequency band.